From the Guidelines
Urea should not be used in patients with severe renal impairment, particularly those with anuria or azotemia, as the kidneys are responsible for eliminating urea and its metabolites 1. The contraindications of urea (carbamide) include:
- Hypersensitivity to the compound or its components
- Severe liver disease, as impaired liver function can lead to ammonia accumulation, potentially causing hepatic encephalopathy
- Severe renal impairment, particularly those with anuria or azotemia, as the kidneys are responsible for eliminating urea and its metabolites
- Pregnancy, especially in the first trimester, due to potential risks to fetal development
- Electrolyte imbalances, particularly hyponatremia or hypernatremia, as urea can affect fluid and electrolyte balance
- Open wounds, broken skin, or inflamed areas, as urea may cause irritation or burning sensations when used topically
- High-concentration urea products should be used cautiously on the feet of patients with diabetes due to potential sensory neuropathy These contraindications exist because urea works as an osmotic diuretic systemically and as a keratolytic agent topically, with potential for systemic absorption depending on concentration and application area 1.
From the FDA Drug Label
CONTRAINDICATIONS: This product is contraindicated in persons with known or suspected hypersensitivity to any of the ingredients of the product. The contraindications of urea (carbamide) are:
- Known or suspected hypersensitivity to any of the ingredients of the product 2
From the Research
Contraindications of Urea (Carbamide)
The following are potential contraindications of urea (carbamide):
- High concentrations of urea can be toxic, particularly in patients with chronic kidney disease (CKD) 3
- Urea can induce molecular changes related to insulin resistance, free radical production, apoptosis, and disruption of the protective intestinal barrier 3
- Urea is at the origin of the generation of cyanate, ammonia, and carbamylated compounds, which can cause biological changes and are associated with cardiovascular and overall morbidity and mortality 3
- Elevated serum urea levels are predictive of increased mortality in patients with heart failure (HF) 4
- High blood urea levels can be indicative of pre-renal, renal, or post-renal pathology, and can be associated with cardiac failure, dehydration, and gastrointestinal hemorrhage 5
Patient Populations at Risk
Certain patient populations may be at higher risk for adverse effects from urea (carbamide), including:
- Patients with CKD, particularly those with high concentrations of urea 3
- Patients with acute kidney injury (AKI), particularly those with high admission urea levels 6
- Patients with heart failure (HF), particularly those with elevated serum urea levels 4
- Elderly patients, particularly those with pre-renal, renal, or post-renal pathology 5
Clinical Considerations
When considering the use of urea (carbamide), clinicians should be aware of the potential risks and take steps to minimize them, including: